The present invention relates to a lead frame of a Cu alloy and a method for manufacturing the same.
A lead frame of an Fe-Ni alloy for a semiconductor IC is conventionally known. Such a lead frame made of an Fe-Ni alloy has a high hardness and an excellent bending strength, but is expensive.
An inexpensive Cu alloy is being considered to take the place of such an Fe-Ni alloy. However, a Cu alloy which simultaneously satisfies all the requirements of a lead frame such as bonding performance with an Au wire, a hardness, a bending strength and the like has not yet been proposed.
When Sn or Ni is added to Cu in order to obtain a Cu alloy of higher hardness, bonding performance with an Au wire and soldering performance of the resultant alloy are impaired. When Zr or Cr is added in order to improve bonding performance with an Au wire, bending strength is impaired.